This invention relates to abrasive products.
Diamond compacts, or PCD as they are also known, are abrasive bodies consisting of diamond particles bonded into a hard conglomerate. The diamond content of such compacts is high, normally at least 70 percent by volume, and generally 80 to 90 percent by volume. Diamond compacts are polycrystalline masses of diamond particles, the bonding being created under conditions of elevated temperature and pressure at which diamond is crystallographically stable.
Diamond compacts are produced with or without a second phase or bonding matrix. The second phase, when provided, may be a diamond catalyst/solvent such as cobalt, or it may be a carbide-forming element such as silicon.
Diamond compacts have high wear resistance, but are brittle. The brittleness of diamond compacts leads to chipping of the working surface or edge during use. In many applications this is not a problem, but in some applications such as in woodworking where fine finishes are required it can present a problem. One of the most widely used materials for woodworking is cemented carbide which has good impact resistance, but nowhere near the wear resistance of a diamond compact. European Patent Publication No. 0 256 829 describes a cemented carbide modified to the extent that it contains up to 20 percent by volume of cubic boron nitride particles. The cemented carbide is preferably produced under cubic boron nitride synthesis conditions so that damage to the cubic boron nitride is minimized.
U.S. Pat. No. 4,525,178 describes a composite material which includes a mixture of individual diamond crystals and pieces of pre-cemented carbide. The mixture is subjected to elevated temperature and pressure conditions in the diamond stable region to create a composite polycrystalline diamond body. The mixture uses pieces of pre-cemented carbide and not discrete carbide particles.
U.S. Pat. No. 5,045,092 describes a method of forming a cemented tungsten carbide article with embedded diamond particles. In this method, the embedded diamond particles are produced in situ. The product is one in which the cemented tungsten carbide dominates.